During the launch of a motor vehicle, the vehicle operator adjusts a throttle of the vehicle, typically by depressing an accelerator pedal, in order to increase the running speed of the engine. Increasing the engine speed increases the amount of torque generated by the engine, which subsequently causes the wheels to turn. The rate at which the speed of the engine can be increased is known as the throttle ramp rate. In some vehicles, only one or two throttle ramp rates may be available, such as a low throttle ramp rate for when a desired engine speed is relatively low, and a high throttle ramp rate for when a desired engine speed is relatively high. Furthermore, these throttle ramp rates may be constant in value. FIG. 1 is a graph of engine speed over time, and depicts a constant throttle ramp rate as used in the prior art.
A constant value high throttle ramp rate is sufficient for vehicles that maintain a uniform weight. However, for vehicles such as commercial trucks, the effective vehicle weight can vary drastically depending on the type and amount of cargo being carried. As a result, one constant high throttle ramp rate is inadequate, as it often leads to excessive acceleration of the engine when the vehicle is light, resulting in jerky starts, or insufficient acceleration of the engine when the vehicle is heavy, resulting in a slow and labored launch of the vehicle.